Combined typewriting and computing machine



H. WHITING. COMBINED TYPEWHIHNG AND COMPUTING MACHINE.

APPLICATION FILED OCT. 2. ISH.

1,329,871 Patented Feb. 3,1920.

H. WHTING. commen vPEwRnmc AND cnMPunNG mAcHmE. APPLICATION FILED UCT.2.19|4 w 1,329,871 Patented heb. d, 1920.

9 SHEETS-SHEEI 2.

H. WHITING. COMBINED IIYPEWHIIING AND COMPUTING MACHINE.

Patented Feb. 3, 1920.

9 SHEEIS-SHEEI 3.

APPLICATION FILED OCI. 2. |914.

H. WHITING.

COMBINED IYPEWRHIMG AND COMPUTING MACHINE.

APPLICATION FILED OCT. 2| 9l4.

Patented Feb. 3, 1920.

@SMQ 9 SHEETS-SHEET 4.

L .L L ...5:

H. WHIIING.

COMBINED TYPEWRIIING ANI) CMPUTING MACHINE.

APPLICATION FILED OCT. 2. I9I4. 1,329,871

' Patented Feb. 3,1920.

9 SHEiTS-SHEU 5.

H. WHITNG. COMBINED TYPEWRITING AND COMPUTING MAHINE.

APPLICATION FILED OCT. 2. i934. w I 1,329,871. Patented Leb. 3,1920.

9 SHEETS--SHEE G.

H. WHITING. ComlNED TYPEWHITING AND COMPUTING MACHINE.

APPLICATION FILED OCT. 2, |9l4. 1 ,329,87 1 Patented Feb. 3, 1920.

9 SHEETS-SHEE T.

APPLICATION FILED UCT. 2, I9I4.

Patented Feb. 3,1920.

9 SHEETS SHEET B uw? u: I@ n. s-Jco GDF! jufc/Lfw.'

EN ihn vari;

H. WHITING.

COMBINED YPEwnmNG AND coMPunNG MACHINE.

APPLICATION FiLED OCT. 2.19l4.

Patented Feb. 3,1920.

9 SHEETS-SHEET 9 w@ Q4 Y TY I UNH-ED As'rigi'rns PATENT OFFICE.

,Rosario WHITING, or NEW Yoan, N. Y., AssieNon, :BAY riEsNE AssIcNMEN'rs, vTo

UNDEBWOOD. .'GOMPUTIN G parloir' or NEWV Yonx.

To'alhckom it concern:

:Be itknown that I, Honn'rlo WH1T1NG,'a

citizen' of the United States, residin in New.

York; city,in the county of New ork and State' of-New York, have invented certain new andh useful Im rovements in Combined Tpewriting and omputing Machines, of W ich the following is `a specification.

g Thisinvention relates to computin machines, more especially to machines a apted to make algebraic summations, and is .herein illustrated asfan improvement on the typefof `machine 4illustrated inthe application' ofA Hansi-Hanson, No.; 626,550, filed May 11,f.191.1-,1 (now Patent No. 1,278,812, dated. September 10, .1918).

The fobject of this invention may be illustratedzb --anexamplay If We suppose a depositor- :1n a'bankxhas a balance on hand of say fifty, dollars and makes out a check for seventy-five ,dollarsfon cashingthis check he has overdrawn his balance the amount of fthe difference,v or twenty-five dollars. Now. in. the'usual method of keepingv bank accounts the balance ofthe depositor is rst runi'i'nto the computing machine asa posi- 'tivefitem and then after the-deposits'have ,beenfrun -into the mathine as positive items, if there are-any, the amounts of the checks cashedV are zsubtracted fromV the amount already registered. The machine in which this invention isgcmbodied then will automatic'ally `take this {larger number, such as the-seventy-ive dollars, from the smaller positive number, such' as' the fifty dollars, and give lthe correct algebraic diierence, which 4.is a debit of twenty-tive dollars.

It has beenettemptedto accomplish this result in machines in which the computing wheels are rotated in'one direction for addition and in the o posite direction for subtraction. Examp es'of this are foundin my rco-pending applications No. 836,693, tiled May 6, 1914, and No. 838,513, filed May 14:, 1914, (now Patent No. 1,288,333, --dated December 17, 1918).

In. the Apresent exempliication'of the invention-a machine of the type` disclosed in said Hanson application 626,550 in which the wheels-rotate always inthe same direction both for addition and subtraction, 1s used to perform an algebraic summation.

` hSpecification of Lctterslatent. Application mea october 2, 1914. yseran No. 864,592.

MACHINE COMPANY, or NEW Yoan.A N. Y., A confou ffcoMBINED A'rrr*EWRI'LINer AND oomrU'rrNG MACHINE4 Patented Feb. 3, 1920.

That is to say, the presentgimprovement is applied to a machine in which subtraction is done by the complementary method, wherein each computing wheel is rotated a full revolution less the amount of the digit subtracted therefrom, therebyagiving in effect a subtracting operation.l l In order to effect algebraic summation, the computing wheels (for decimal computing) are provided withltwo series ofvnumbers ranging `from ;0 to 9, one of-the seriespreferably being' inone color, such as black, and theother seriesbeing in another color, Vsuch as red, for the purpose of dis-l tinction-f The two'series ofnumbers ascend in opposite directions around thecomputing or number wheels,l alternating digit for digit with each other. The di its of the two series'on a computing whee are also arranged soV that two juxtaposed digits, one from each series, may be paired so as to give the sum of nine. That is to say, the digits are arranged with thecomplementa digits or co-dig1ts in juxtapositlon to eac other, so Vthat if a number is exhibited `in one series and an algebraic summationhas been made, a shift may be effected to disclose the co-digits or complements of the number exhibited. J

To effect the change from exhibiting one set'of digits, say ,fthe'black digits, to the other set of digits, say thered digits, and vice versa, there is provided ashutter or shield which `is arranged to disclose or indicate but one line ofl digits at 'a time, but

which may be shifted so as to alternatively disclose either a line oil-black digits or'a line of 'red'Y digits, yindicating respectively that the -resultfothe computation is' either a. positive or anegative quantit In prior inventions along the line of algebraic computing machines the shifting of the shutter orsimilar indica-ting mechanism has been predicated on the Ypassing through zero, in a reverse directionto vthe direction ofascenduncy of the numbersfexhibited, of the computingi wheel ofhighest denomination when ma ing an algebraic summation, that is, taking a larger `number from a smaller number exhibited. v

In the resent instance l the computing wheel of highest denomination never. passes that of necessity tens will through zero in .a reverse direction as the computing wheelsV always rotate in the same direction, and in fact when making an algebraio summation in one,diretion, that is, in taking a larger .lne ative number from a sma'ller positive num' er exhibited, the computing wheel of highest denomination does not even reach zero.` ,4

As explained in said Hanson application 62,5 0,tq .elect an prdinary com 'lementary subtrattion in this type of mac me, all the computing wheels not-having a number subtracted therein are rotated nine-tenths of a revolution', -with the-provision .of an extra unit added to`theunits computing wheel so e carried, and all the-computing wheels of higher denomi nationthan thoseffhavino digits run in in a shbtraz'ting manner, will be rotated a complete revolution, that-'is ten-tenths of a revolution.

Nowthen in this type of machine when an algebraic summation is made, that is, a larger negative number subtracted from a smaller positive vnumber ez'zhib'ited,` the comle'ments run-'into the computing'4 wheels will hersoffsma'll' that tens -wlll not be carried sloth'a't the'c'oinputing wheel of highest denomination ewill 'not arrive at l0 but will remaintat 9. 'Therefore one ofthe conditions denoting an algebraicl summation and bringingthemechanism for effecting an algebraic summation into 4play is'predicated on the computing `Jvheel of highest denomination remaining at 9 when subtracting l`a la i.rger negativelnumber from a smaller positive number. That is to say, Whnthe-shift of theV shutter should be ma'de from black to red figures, the highest computing wheel will stop short of going to and will remain at 9,

To enable the easy action of the machine and Vto avoid confusion to the operator, a supplementary -compu-ting'wheel of highest denomination maybe used which may not be afcomputing wheel'and which is only driven when "a 'subtractin operation isv taking place, Whether an` a gebraic-subtraction or a' normal one". This computing wheel of highest denomination is provided with a 'special rack` bar having a single Lpin correspondingto Vthe H9 pin. 'This 9 pin is set Vwith the other 9 pins in a manner comlmo'n to thistyp'e o f machine when setting themachine for subtraction.

The'gcoinputihg Wheel fof highest denomination (vin, the Supplementary wheel) will la'lwfays 'be-rotated nine'l points in subtractiox 1,'andV ifit is an ordinary subtracting operation, "1?v will be carried therein so that it will v'go to zero.y If, however, an algebraic-subtraction is ,taking place a carryover action will not happen so that this highest' computing wheel will be left exhibiting' 9. Advantagel is taken of this state of aii'airs to enable the shutter t0 be shifted from showing black positive numbers to showing red negative numbers when the highest computing wheel stops at 9 or at a position corresponding thereto. This means that three conditions must obtain in order to shift the shutter in subtracting a largernegative number from a smaller positive number; that is, the shutter must be showing a black or positive number, the machine must be subtracting, and the 'highest computing Wheel must stop at a position corresponding to thc showing of .9.

These three facts are made use of by providing three interponents, one for the shutf vter. one for the computing wheel of highest denomination, and one for the subtraction-setting mechanism. ponente are shifted: by their associated parts so that, when the shutter is indicating black numbers, and the highest computing :wheel stops at 9 or at Yazposition .corresponding These `th ree interthereto as would happen in an" algebraic subtraction, with the machneacting to efect a complementary subtraction, :then all three of these interponentswould. be `in a-linement with each other-'so that they can transmit an impulse taking place subsequent to the running up of a number and subsequent to the action of the :tens-carrying mechanism, which impulse can be used to initiate an acti-on of a shifting mechanism similar to a tens-carrying unit which will shift the shield or shutter from exhibiting black numbers to exhibiting red numbers.

On the other hand when the shutter is in a position corresponding to the showing of red or negative numbers and positive numbers are added thereto, a point will be reached Where the added positive number is greater thanthe negative number exhibited, which will eiect an algebraic summation passing through zero'in an ascendingv direction so that it will be necessary to shift from showing-red or negative numbers to showing-black or positive numbers, To do this three: conditions'must obtain; that is, the shutter must be indicating red ornegative numbers, the highest computing Wheel must pass to zero or a position corresponding thereto, and the machine 'must be adding. 'The three interponerits above mentioned under these circumstances will again occupy a position in alinement with each other, although lying in a ditlerent zone than their other position of alinement. They will then permit a transmission of an impulse from the general operator of the computing mechanism which, as before, enables a shifting of the shutter, but this time from showing red or negative numbers t0 showing black or positive numbers.

The mechanism is so arranged that no matter in which position the shutter is standing, if it moves, it will be shifted to the opposite limit of its throw, that is, if it isvshown =red, to showing black, or if it is showing b ack, to showing red, so that the shutter 'determines by iisown position when "6= andf'how itwill be shifted. '.i i

fIn; an ordinaryrcomplementary subtracting machine it is necessary to insert an extrafhnitfin the' unitswheel when the comp'u'ting wheel of highest'i denomination `is to reachfzerofand not pass through it. Ordi-` narifly thi'sfis'donelwithout reference to the c'bfhptng vih'eel "of highest denomination by mechanism entirely distinct therefrom and igenerally takinglplace in advance of the niovement'cf-th'e computing wheel of highest-denomination,' in fact, often causing it to move to zeoJIn order to obtain atrue resultin an algebra-icY summation by a complementary subtracting-machine it is necessaryto refrain flcm inserting this extra unit whenmakingan'algebraic subtraction in going 'from1a:blaclpositiveglumber to' a nega-y tiedlnumberjiii'r'Il ab i l w A On the otherl hand in going from ared negativefumbr to ai ptsitivoblacklnumber in ascending through-'zero Ywhile adding,A it is'necess'ary'toiinsert a"extra' unit tothe units; i computing'j wheel. s ",Inasmuch as the highest"coniptin'g wheel is an'idle computing' wheel and =onlyfrotates when subtracting or whenirr-adding below-zero and l is ca'ri'iedjthereto? from the computing Wheel nextV 'kivter4 in denomination, 'advantage is taken of th' computing wheelof highest denomination which always rotates in the same directioilA by causing it in passing from 9 to Oitoj trip aspecialfinserting or boosting mechanisn which`r "rotates the vcomputing wheelof lowest denomination,- that gives theilnits oilip'ltigi'rvvheel an added Step. Thisy insertingff or boosting mechanism may be normallyset'for'action at any actuation oftheigeneral'operator of the computing machine so that itwill always be ready' ffor action; butT'it-j is'n1y tripped `into action when the 'computingiwheel 'of highest denominatiompassesto *zero either in `an nonalgebraicfsubtracting operation or in" an addingioperation', Vpassing up through zero from an exhibition of ared negative number to the exhibition of afblack positive num- 'Thectensicarrying mechanism in order to complete the computing action, may have a double action during the return stroke of the general operator so that the computing wheel of highest denomination may start the insertion in the computing wheel of Ylowest denomination, and this action1 vif necessary, may bevlatcrcarried to the computing wheels of'.hiher Adenomination than the units computing vWheel. .f The interponents receive'their impulse,

if in alinement, between the first and second 65 Lactionsof'the tens-carrylng mechanlsm so that theyI will. have the benefit oflthe,= rst tens-carrying L action Y, to determine` t Whetherf the summation is :tn-algebraic fone. orunot Under normal conditions when not effecting an algebraicfsummation, the interponts; are notall in alinement with each 'otheryiso that 1they-will fnottransmit a direct impulsez with the-.result that the shutteriivilljnotbe; shifted from itsposition but williremain in statulquanp` j r. Mn-Hw Ani/ i.,

Other V.'lea'turesf and' advantages iwillgheneel 'mafterflppealgmijidfitis mi? M u'rffiirswi/'m In the accompanyingfdrawingsyw- Q g Figure .l `is va :vertical section from* ifi-ont,V to rear takenthrougha Hanson' :combined typewriting and a computingf mechanism showing my invention rappledgtheretoi i l Fig. Ziis a horizontal-isectionztaken above thepcomputing mechanismqxfi andnnm di! Fig. 3 is an enlarged fverticaliisection foi the rear portion'wofethe .computing mecha. nisml showing the subtractionsettingmechas nismfinutheivery actief settin ,fior-(sublimes tionfanri before-it :has returne al passive position@ 's ffii-ii; 1f-.irioja-milio ed: f Fignyft islfan enlarged horizontailfisviehl partly in section of thefpin-settin ilinkagest showing Athe arrangementfor shi 'ngjgom an adding Setting toa-.subtraction getting, the linkages being disclosed'invtheirfadding l 9s settingr conditi0n.,fV fw A' ygi-M im Fig. 5 is aviewf in elevation partly; in-section, showing the ylinkages andtheir manner of superposition above the-'nestleofvpinsvon the denominationalmembers.:` c I-OO Fic. G is detail perspective viewgshogwing the idie computing=whee1-ofiihighestdes nomination with rthesxriechani'sm thereon 'for setting the interponentv 'which -occupiesone of three positions corresponding toftheposid D05 tiouing `of the computing wheel .ofhighest denomination at an exhibition ofgfi., -i10,? or anv other digit. The computing AWheel of highest denomination` and the :parts governed' are shown as ata; point? correspond# 110 ing to the exhibition of 8? with-,themshinfr arms out of engagemebwitheach other: the interponent 1 occupying` a i passiiienposi ZOII.' il 3' -l' :;.;EV. i Q- wir' 'ivi Fin'. 7 is a detail view in vertical section` n.5 showing the toothy on the highest; computing' wheel as aboutf'to 'trici theiocknforgethewnserting 'or boosting :mechanismsoperartiuis on the units computingwhel. A'IIhisi-foccurs when the computing wheelioghighest 120 denominationA passes 'from .au 'positioncorresponding to the showing of 9?it'o a, Lposition corresponding to the; showing" ofy `0. This view also shows thevsingle pinioorrespending toa .9," -pinv for {thc-idley coinpiit- 1-25 ing wheel of highestvdeno'minationaand the means-for'settingthe same.f 1 fr Fig.' 8 isfiafdetail-plan view showing fthe relation osthe denominational driving 'meml bers tothe various computing*Wheelsc l? 130 Fig. 9 is a skeleton perspective view showing the units computing wheel and the idle computing Wheel of lnghest denomination, together with the three interponents operated individually by the shield, computing wheel of highest denomination, and subtraction key, in which three interponents are shown in'alinement with each other corres onding to an exhibition by the shield of lack numbers, a positioning of the computing Wheel of highest denomination corresponding to the exhibition of 9, and the machine-in a subtracting operation after the subtraction key has been actuated. This position of these three interponents in this alinement with each other will only occur when makin an algebraic subtraction of a larger ne ative number from a smaller positive numer exhibited in black. The general operator is shown on its return stroke midway thereof about to bring into play the shutter-shifting mechanism through an operation Vofthe Ithree alined interponents.

Fig. 10 isia detail persepective View of the pin-restoring plate which returns the pins to-an *unset position at the end of a computing operation.

Fig. `11 is a skeleton perspective view showing in `:full lines the shutterinterponent out of alinement with the highest computing wheel interponent and the subtraction or character computation interponent, so that anV impulse would not be imparted therethrough. In dotted lines the character computation interponent is shown in its subtracting position, whereas in full lines itis in its adding osition.

Fig. 12 is a detai view in elevation partlyT in section, showing how the shutter-shifting mechanism will shift the shutter from inclicating black, as it does in this figure, to indicating red.

Fig. 13 .shows how the shutter-shifting mechanism'is capable of shifting the sluitter vfrom Vindicating red to indicating black.

Fig. 14 shows the shutter-shifting mechanism inthe act of shifting the shutter from indicating red to indicating black, the shutter having` not quite completed its movement.

Fig. 1'5 is a detail perspective view of the starting pawl which brings the shuttershifting mechanism into play; that is, which shifts the shutter-shiftm mechanism to such a position that it wil come within the sphere of oeration of the tens-carrying asslsting sha Fig. 16 is a detail sectional view showing a position successive to that illustrated in Fig. 7 wherein the tens-carrying tooth on the computin wheel of highest denomination, that is, ie idle computing` wheel, has just tripped the lock for the inserting or boosting mechanism for the units computing wheel as the computing wheel of highest maas-r1 denomination passes from a position corresponding to the exhibiting of a positive 9 to a -positive 0.

Fig. 17 shows in dotted lines the inserting or boosting mechanism in the position 1t would occupy after having rotated the units eomputin wheel an extra step, and showing in fu 1 lines the inserting `or boosting mechanism returned to its normal position and locked in suchv position, the tens-carrying tooth on the computing lWheel of highest denomination having cleared the trip for the lock.

Fig. 18 is a developed view of the periphery of a computing Wheel showing the relation ofthe two series of digits thereon Which ascend in opposite directions, the heavy numbers indicating the black or positive digits, and the dotted numbers indica-ting the red or negative digits.

Fig. 19 illustrates the relative positions of the three interponents when adding. above zero, that is, in the normal .adding` operation.

Fig. 20 illustrates all the three interponents.

Fig. 21- illustrates the mechanism for shifting the interponent corres ending to thc idle computing Wheel of lighest denomination, and showing the same in a posltion corresponding to the exhibition of positive 8. ponent will be the same for the exhibition of any other digit except 9 or 0. Such position will only occur when the computing Wheel of highest denomination is rotated.

Fig. 22 illustrates the structure shown in Fig. 21, with the exception that the interponent has been shifted to a position corresponding to the exhibition of 9, which position will occur when making an algebraio subtraction of a larger negative number from a smaller positive number exliibited.

Fig. 23 is a view of the parts shown in F igs. 21 and 22, except that the interponent has been shifted to a position corresponding; i0 the exhibition of a black positive 0"3 which will occur after all normal adding or subtracting operations above zero and in an adding operation belovcr zero where a larger positive number is added to a smaller negative number, making an algebraic summatlon.

Fig. 2li-is a detail section in elevation showing hovs1 the denominational Vmembers or rack bars drive the computing wheels solely in one direction.

Fig. 25 is a vertical section showing how the three interponents when in aline-ment can transmit an Vimpulse to bring into play the. shutter-shifting mechanism. i

Fig. 26 'is an enlarged vertical section talcen from front to rear showing the shuttershiting controlling mechanism and parts of possible positions of This position of the inter- `tate Qn a carriage 7.- The carriage 7 is Y Yadvanced step by -step by a spring barrel (not shown) under the control of an escapement mechanism indicated in general at 8.

This escapement mechanism includes a rack 9 hin on the carriage 7 so as to be movlable into and out of engagement with a pinion 10 connected to an escapement wheel 11 which is controlled by fixed and movable the latter may dogs 12. The dogs 12 are' in turn controlled by a universal frame 13 which is rocked at the actuation of any one of the type-bars 5 by heels 14 carried thereby. In a dition to the step-by-ste movements of the carriage given jum movements by a. tabula'ting vmechanism inc udng keys 15, plunger stops 16 and carriage-carried stops 17.

Inaddition to operating Athe type-bars to print the digits the numeralikeys 2 operate pin-Settim' mechanism 18 toset pins 19 on denominational members 20 so as to determine the'ertent of the movement of thelatter. These denominationalmembers 2O are Yprovided at their forward ends with racks 21 (Figs. 9 and 24) so that they form rack vmentioned Hanson application.

inational columns. That is'to say, each ofY the denominational members 20 corresponds to a single denomination of writing and is provided, in the case of ordinary computations, with a row of nine pins ranging in value from 1 to 9 In order to bring each row of nine pins within the range of the pin-setting mechanisni 18,tliere `is provided on the carriage 7 of the typewriter a tappet 37 which when the carriage arrives at a computing zone, is raised by a zone-controller 38 to ysuch a position that it will be effective torock in succession a series of jacks 39. These jacks 39 depress individually thrust rods 40 to rock levers 41. The levers 41 are arranged individually tov operate transposition lin-kages 42- in a manner 'described in the above The purpose of these linkages 42 is to raise the rack bai's or denominational members 20 one by on so as to bring the rows of pins 19 individually into the sphere of operation'of .the pin-settin mechanism 18. Inasmucli as bars which engage pinions 22 so as to driveol which are operated successively from right to the computing or dial wheels' 23. The

ars 21 will only drive the computing wheels' on the forward stroke thereof. This is accomplished byA a ratchet wheel 24 on each gear 22 engaging effectively, when rotating in a direction indicated by the arrow in Fig. 24, with a spring-pressed pawl 25 on the corresponding computing wheel 23. The rotation of the gear 22 in the opposite direction will permit the awl 25 to click idly over the ratchet wheel) puting wheel 23will not be disturbed.

To operate the pin-setting mechanism 18, which may be substantially likethat shown in Hanson Patent 816,319, granted March 27, 1906), each numeral key 2 is provided with a thrust link 26 (Figs. 1 ando) which engages an arm 27 on a rock shaft 28. The rock shafts 28 are provided with arms indicated in general at 29, which engage pins 430 on linkages 31. ,Each linkage 31 com prises an upper reach 32 and a lower reach 33 connected inparallel spaced relation by 24 so that the conv driving racks 48 on the`si es of t e `ieft, will raise the denominational members .bars v20 serve as a means for determining the extents of movement of the rack hars 20 and in amounts corresponding to the particular pins set. To accomplish this movement there is provided a general operator indicated in general at 43. This eneral operator may be actuated in any suitable manner either by a motor orfb a hand crank 44'.secured to a shaft 45 W ich has one or more segments 46 ineshin with inions 47 neral operator 43. When the hand cran 44 is swung forward it will move the general operator 43 forward so as to bring a cross bar 49 o'n the general operator into engagement with such of the pins 19 as have been set below their fellows, carrying these pins and he rack;bars. on which they are mounted l orwarl to rotate the computing wheels 23 a corresponding amount. l .H a number has been previously run into the computing Wheels 23, some of them may complete a revolution so that itis necessary to car-y from a lower computing wheel to =a..h'1g ,er oomlputing wheel. For this purpose each of t e computing wheels 23 is proyid with a tens-carrying or starting tooth 1 dg. 2.4),which once 1n each revolution engages .a mutilatedgear 51 so as to shift the saie sli htl that is, one-ninth of a ,revolution fac of these mutilated gears 1-5 51 has'every third tooth cut away so as to :.oti'er under nonftens-carrying `conditions a Vblank surface to anlassociated one of a series of segments 52'. The segments 52 will nor- ,xn llysweep idly through the blank portions A- oijtheinutllated gears 51 without any action,l It, however., a tens-carrying tooth 50 has, shifteda .mutilated gear 51 to bring a d' u llgtoothgin the range-of the associated'segment, then this segment will drive the mutiilatedlg'ear. a further distance of two-ninths lof'a revolutiominaking a third of a revolutionin all. Q The mutilated gear (see Fig. 26 in each instance .has a three-toothed or tri ent gear 30 5:3 Secured thereto and normally out of mesh .fywitl agear 54 on the next higher computin fwheel "but, adapted to mesh therewith an fdrifve that wheel. There are ten teeth on each rear 54 so that a movement of the gear .35 5l w ien the associated gear 53 moves vthrough one-third of a revolution, will move Ithegear5-t one tooth orone-tenthof a revo- Alutiorn therebyA carrying tens from a lower computing wheel to a hi her computing (e0 wheel, this beingV substantia ly the carryover sh wningtheHanson patent aforesaid'.

he', 'assisting Q ments 52 are spirally 'moited on a shaft. i 5 so that. they Will come into action` Vstr t'ijir'ng with the .45 corresiondli n gy A,to theunitsncomput mg Wheel, proceeding successively to .gie-tens'. hundreds, thousands', and' so on. will'enble tens to be carried successiv romuiits to tens, from tens to hun from: liundreds to thousands, and

soon. 'y

T e shaft'55 is rotated on the return stroke of t elger'iei'al' operator 43 when the crank moves' baUk'WardIy, as it is desirable to 55 liave, the: tens computing operation take i ersfon the co pfut' wheels b fthe rack elem .Thes IP ng y ismafsegnients 5 glace subsequenhto, the running up of num- ,which carries" the asmay ,receiveits drive @0. any'lsiiita gleIsource such as the eneral operator/4531 or this ."ur ose` an id e gear .-56 meshes with onelofrlithd? racl'r's the ssneal .asentar and drives a: Pimm 57 mounted on the shaft 55. Tlie gear 57, however, is not fixed, on the shaft 55 and 459 (Fig. 1

only rotates the latter during the return stroke of the general operator. To arran e for this action the gear 57 is connectib e to the shaft 55 by the usual one-way actin ball and socket clutch 58. This ball an socket clutch permits the gear 57 to rotate idly during the forward stroke of the general operator but connects the gear 57 .positively to the shaft 55 during the return stroke of the general operator. The ratio of the gear 56 to the gear 57 and to the rack 48 is such that the shaft 55 will be given two complete revolutions during the return stroke of the general operator so as to give two possible tens-carrying operations for a purpose to be'described.

Thismaehine is arranged 'to take care of subtracting operationsas well as adding operations, and it 4acconifnlishes them by what is known as the complementary method. This complementary method consistsin rotating the `computing wleels through complete revolutions less amounts corresponding tothenumeralkeys actuated inac'oordant denominations, which is equivalent to 4rotating the computing wheels backward amounts corresponding to the numeral keys actuated, although the computing wheels are always rotated in the same'dmection` for either addition or subtraction.

In order toa'djust .the machine for accomplishinga subtracting' operation itl may be set by any desirable automatic mechanism, or manuall Vby means-of a subtraction key i. This subtraction key 59 has many of the connections shownin the Hanson application aforesaid and when depressed rearwardly against the tension of a spring 60,forces rearwardly al subtraction rod 61 (Figs. 1 to 3). The' latter en -ag'es at 62 with an arm 63 secured to a sha 64. This shaft. 64 is rovided with a bail 65 which underlies al of the denominational members orrack bars 20, so as to raise them simultaneously. The purpose of raising the rack ,bars in this manner isto enable all yof the SV-pins to be set thereon. For this purpose the subtraction rod 6l is provided with a pin 66 which enga es a lever 67 seeuredlfto a shaft 68 on w rich is secured a bail 69.` .This bail overlies and engages all of a series of levers 7 0 which are connected to the 9, pins on each of the bars 20. It Willlthusibe 'seen by the concomitant action of the bars' 20 and the bails 69, that all of the 9 1pins will be set. This is done to provide or the rotation of all the computing wheels not havin' anumber run in by a digit subtracted in the accordant denomination. 12 In addition to so setting all the 9 pins the pin-setting' mechanism 18 is adjusted from a condition inwhich the set `pins 19 correspond tothe direct values of the numeral keys 2 actuated, to a condition in 130 its Lessen pin, which' is 8, will belset if fthe 2 A key is struck the complementary pinvhich is 7, will be set; if the 3* key is struck le complementary pin, which ii. 6, will set, and soon.

Ineffe ng this readjnstmeni,= the shaft l68 (Fig. fg which was rocked at the rearward` movement of the subtraction key rod 61, wi1l swin forward an arm 71carri'ed thereby, whic in turn will rock forivard a shift rail 72 pivoted 'at its upper edge and engaging at its lower edge in a series of alined notches 73 (Fig l) provided in the rock shafts 28. This will force the rock shafts 28\forward against the tension of a spring 74`(Fig. 3) in which position they will be locked by` a latch 75 engaging the rail 72, this latclr being sprung to its work by a spring 76. The readjustment of the rock shafts 28 changes the pin-setting mechanism from a condition in which it sets the pins for ad 'tion, to a condition in which it sets the complementary pins for subtraction. In explaining this phase, the rock shafts 2S and their arms 27 are designated (Fig. 4) by t 1, 2, l 3, 4, (i 5:9 t 6, 7, 8, 9, corresponding to the values of the keys which actuate them. The linkages 31 are indicated successive-ly by the responding to the values and extents of movement of the pins 19 which they set. Each of the rock shafts 2S is provided with an adding arm indicated respectively by the reference numerals 1^, 2^, 3^. 4^, 5^S, 6^. 7^, 8^, 9^, which engage with pins 1W, 2W. 3W, iw, 5W, 6W, rw, ew, 9W, mi um links 1L. 2L, 3L, 4L, 5L. 61'. ""3 HL. 9L, respectively. The rock shafts 28 are also provided with subtracting arms 15, 25. 3S, 4S, 5'. (is, 7S. 85, which are arranged to engage respectively with pins 1", 2P, 3P, 4P, 5P, 6P. 7", 8*. on the links 8, 7", 6L, 5l'. ll'. 3L. 2L. l, respectively.

It will be noted that tlu` adding and suhtracting arm 5^? for the rock shaft 5" is common to both the adding and subtracting series as it lies between the 5L linkage and the 4L linkage, 5 being thc direct value for the 5 key. and 4 -bcing the complementary or co-digital value for the 5 key. l

When the rock shafts 28 were shifted en bloc by the actuation of the subtraction key 59, the adding arms 1^, 2^. 3^, 4^, li, 6^, 7^, 8^, 9^, were shifted out of engagement with thepins 1W, 2W, 3W..-l'. 5w, 6W. 7W, SW, 9W, while the subtracting arms 1S, 2S, 3S, is. 5, 6` 7 s, 8s, were shifted into engagement with the pins 1", 2P, 3P, 47,5", (3", 7", 8*. This then enabled the numeral keys 2 to actuate the4 linkages 31 ranging from 1" to 8l' so that they would set pins accordant with the .complementary or cli-digital values of the numeral keys actuated.

When any of the pins from 1 to `8 are set by the striking of a numeral key 2 in a subtracting operation, it is necessar to unset the 9 pin in the same denominatipn, that is, on the same bar 20. Fo' this pup.

ose the shifting of the rock shafts 28 also Eringsa series (Fig. 4) of arms 1'?, 2, 39,5@

i, s, 6R, e, 9, on the mak 'Shafts 28 into engagement with a series of ins RW on a pin-restoring linkage RL. his 1nrestoring linkage 1s similarto the other Imkages, with thc exception that the. lower reach overlies the tails of all of the 9 pin levers 70. It will be seen that this pin-restoring linkage 'will be operated when any of the numeral keys 1 to 9" is actuated in `a. subtracting computation so that the 9 pin on which ever denominational member 2O happens to he raised will be unset with the setting of another pin in the case of the keys from 1 to 8. There will be no pin set at the striking of the 9 key as the complement of nine is zero.

The setting of the pins in this complementary manner will enable the number to be subtracted from a number already ex':

h ibitedby rotatingall the-computing wheels acomplete revolution less the values of the keys struck in the denominations corresponding to the several computing wheels. ln a direct or non-algebraic subtracting operation. however, provision has to be made for the boosting or inserting of an extra; unit to the units computing w ieel in order-to give a true result. To provide for this there is provided a special or supernumerary' bar 77 (Figs, 5 and 8).- This supernumerary har ,77 is provided with.V a pivotally mounted dog 78 (Figs. 1 and 27) which is engage/d un its abrupt surface 179 during the initial portion of the forward motion of the general operator by its cross bar 49. The cross bar 49 will cari-'v the supernumerarybar 77 for-v ward untillthe front end thereof engages and rocks one arm 79 of a bellvcrank lever 8l) so as to compress a spring 81 (Fig. 26'). Piv otally connected to the bell crank 80 there is provided apawl or dog 82'which is yieldf ingly held in engagement with a ten-toothed gear 83 on the units computing wheel by a spring 84. The supernumerary bar 77 does not travel, however, the full length of stroke nf the general operator, but a stationary trip 180 engages a cam surface 181 on the dog 78 and disengages the same from the cross bar 49 against the tension of a spring 182 which normally holds the dog 78 to its work. The bar 77 settles slightly Where it is held in its forward position by a. springpressed latch 183 which engages in back of a. pin or projection 184 on the bar 77. This tripped.

latch 183 is tripped at the completion of the forward movement of the general operator 43 by the return cross bar 185 engaging one arm of a bell crank lever 186 connected by its other arm 187 to the spring-pressed latch 183. This permits a spring 97 to return the bar 77 to its normal position clear of the inserting or boostingin mechanism. The gear 83 corresponds to the tens-carrying gear 54 on the other computing wheels.

When this inserting or boosting in mechanism, including the bell crank S0 und the driving paivl 82, is set in this manner, it is locked in position automatically by :i latch 85 engaging the arm 79. The latch is urged to its work by a spring SG and maintains the same in operation until It will thus bc seen that the inserting mechanism for boosting the units wheel an extra unit if it has been previously sprung, will be automatically reset at any forward operation of the general operator.

rIhe tripping of the latch 85 to its releasing position shown in full lines in Fig. 16` is controlled from the computing Wheel of highest denomination as the latter passes from a position corresponding to the exhibition of 9 to the exhibition of O. In this particular instance a special computing wheel of highest denomination is provided and indicated specifically at 87 6 to 9, 16 and 17). This special computing Wheel of highest denomination may be in reality an idle computing wheel and not be used for actual computation. ln fact. it may be concealed by the casing oi' at least be bevond the range of vision, although it may have numbers inscribed on its surface for the purpose of reference and to designate the different positions of the wheel. This idle computing Wheel 87 may be provided with a gear 88 (Fig. 7) similar to the gears 22 on the other ycomputing wheels. which meshes with a rack 89 on a rack bar 90 so as to be driven by the latter.

The connection of the gear 88 to the special idle computing wheel 87 is the same as that for the other computing wheels as illus trated in Fig. 24, so that its rack bar 90 will drive it onlv in one direction. The rack bar 90 is higher in denomination than any of the other rack bars 20. and is provided with but a single nin 91 which is arranged in alinement with the 9 lpins on the other rack bars 20. This special pin 91 will be set when the other 9 pins are set for a subtracting operation by the bail 69. Provision is therefore made at everv subtracting operation, whether algebraic or non-algebraic. for a nine-tenths rotation of thespecial idle computing wheel 87 of highest denomination.

In an ordinary subtracting operationthat is, a p non-algebraic subtracting operation,

tens will be carried in the usual manner by tenscarrying mechanism similar to that for the other computing wheels, to the special computing wheel of highest denomination so that at every normal subtracting operation the computing wheel 87 will be rotated one revolution. nasmuch as the computin wheel 87 is started at a ositon correspon ing to 0 at the line ci) sight, it will come around to this same position after a complete revolution. As the computing wheel 87 moves from a position corresponding to 9 to a position corresponding to 0, that is, as indicated in Fi 16 where it has completed a part of suc movement, a special tooth 92 will engage an arm 93 of a tripper which includes a rock shaft 94 on which the arm 93 is secured and a second arm 95 also secured to the rock shaft 94. The arm 95 is connected by a' link, arm and rock shaft 96 to the latch 85 .so that as the computing wheel 87 asses from 9 to 0, that is from the Fig. position through the Fig. 16 positioii to the Fig. 17 position, the latch 85 will be tripped to the Fig. 16 osition, perinitting the spring 81 to act so t at the units com )uting wheel will be advanced one unit by t e boosting in or inserting mechanism.

Inasmuch as the carryover of the extra unit necessary to move the highest computin' wheel 87 from the 9 position to the 0" position, generally takes place onV the return stroke of the general operator and at the end of the first tens-carrying operation, the bar 77 has had time to be moved away by the spring 97 to a position clear of the arm 79 permitting the bell crank 80 to rock. Of course, on the subsequent forward movement of the general operator, the inserting or boosting in mechanism will be reset by its special bai' 77, and the tripping mechanism for the latch 85 having been cleared by the starting tooth 92, will permit the latch 85 to once more lock tlie boosting in or inserting mechanism in its set or primed condition.

In makin a complementary subtraction below zero t e inserting or boosting mechanism may happen to be tripped on the forward stroke of the general operator. For this reason the supernumerary bar 77 is locked nearly at its forward osition so as to prevent a complete action of the inserting or boosting in mechanism. It is, however, not locked in its extreme forward position but settles onto the latch 183 a slight amount sufficient to permit the arm 79 to move beneath the latch 85 so that the latter cannot rengage this arm until after the inserting or boosting in inef hanism has acted on the return stroke of the general operator.

In speakin of the exhibition of 9 and O or the positions corresponding thereto in connection with the computing wheel 87 of highest denomination, it may be noted that this computing wheel need not have numbers thereon, and the designations given are merely used to distinguish between positions where the computing wheel 87 has made nine-tenths of a revolution and ten-tenths of a revolution.

It has been shown then how in an ordinary subtracting operation the pins 19 are set up according to the complementary values of the numeral keys actuated, and that the special supernumerary bars 77 and 90 are given movements corresponding to one step and nine steps respectively, so as to provide for the insertingof the extra unit to the units computing wheel. On the return stroke the tens-carrying or, in eii'ect, borrowing takes place, and the machine is tripped so as to return to a normal adding condition in the manner described in the Hanson application 626,550 above mentioned. In brief, this latter is accomplished by a tri per 98 enga ing one arm of the latch 7 5 anc releasin t e shift rail 72, so that the spring 74 wi l be permitted to act to return the pinsetting mechanism to an adding settin state.

Provision is made for the restoratlon of all set pins, whether in adding or subtracting, by means of a pin-restoring` plate 99. To operate this plate at approximately the end of the return stroke of the General 0perator 43 there is provided on this general operator a one-Way acting dog 100 which may be oi the usual type (Fig. 3) and which trips idly by an arm 101 fixed on a shaft 102 during the forward stroke of the general operator. A spring 103, however, returns the dog 10.0. to an operative position so that during the return stroke of the general operator, it will engage the inclined back surface of the arm 101 and thus rock the shaft 102 to bring a second arm 104 thereon up against the plate 99 so as to slap the latter up against the under side of the pins 19, moving them to their unset position.

The plate 99 is mounted for horizontal movement by a plurality of bell cranks 105 which are pivotally mounted and are connected by one or more links 106 so as to rock in unison. Provision is made on the pin-restorin plate 99, as seen in F ig. 10, for the unsetting of the special pin 91 on the highest denominational rack bar 90, by forming an extension 107 on this plate.

ln addition to making simple additions and subtractions with this machine, provisionis made whereby either an algebraic subtraction or an algebraic addition may be made. For this purpose each of the active computing or dial wheels 23 is provided with two series of numbers, as illustrated 1n Fig. 18. These two series of numbers may be distinguished from each other in any suitable way, as by diii'erent colors, one series being in black, and the other in red, the

black series being indicated at Fig. 18 by peavy lines, andV the red series by dotted lues.

It will be noted that the black series, which in this case are taken to indicate positive numbers orcredit items, ascend on the computing wheels 23 in such a direction that the normal rotation of the computing Wheels b v their rack hais, will cause them to advance in successive ascending order, as 1, 2, 3, 4, etc. On the other hand, the red digits on the computing or dial wheels '23 ascend in the opposite direction so that as the'computing wheels are rotated, these digits will come into view in a descending direction, as 0, 9, 8, 7, 6, etc. The digits of one series alternate with the digits of the other series, so that two digits, one'irom one series, and the other from the other series, are in pairs which give the sum onine.- :That is to say, every two H adjacent digits, one-taken from one series, and the other takeny yfrom the other series, may be considered to be codigits orcomplementslof eachfother.v The black o r ositive digits may he 4used for computing a ove Zero with a positive -or'cr'edit alance `in the totalizer, while thewred or negative digits may be used .for computing below zero with a debit balance.

Aln order to avoid confusion it is desirable to exhibit, or at least indicate only one set of digits at atime. For this purpose there is Vprovided an indicator in the `form of a shutter or shield 109 overlying the computing4 wheels, 4which has'a` si ht opening or slot 110 (Fig. 9) of suiiiclent eripheral magnitude to exhibit but a sing e line of digits on the several computing.' wheels. The casing 111 of the computin mechanism'may be also provided withV a, slght opening 112 which however may be of suiiicient magnitude to disclose one .or the other' of the lines of digits according to the position of the shutter or shield 109. A shaft 113 loosely supports the computing wheels 23 and also forms a pivotal support for the shield or shutter 109 so that the latter can be shifted from showin black digits to showing red digits, and vice versa.

When computing in positive items above zero, the shutter 109 is located in the position shown in Fig. 12 where it will exhibit black digits. When computing in negative items below zero the shutter 109 will occupy the position shown in Fig. 13 where it will exhibit red digits. The computing wheels 23 always stop at the same oints or intervals of one-tenth of a revo ution, and the change is made from showing blackto showing red digits and vice versa, bv a shifting of the shutter or shield 109. The justitie or alined position of the computin wheels 23 is assured by spring detents 114 i 26) individual to all the computing w eels.

These detents cooperate with detents 115 which act on the tens-carrying units to insure the proper stoppin positions of the computing wheels 23 an the tens-carrying mechanism.

There are4 two conditions when it is necessary to shift the shield or shutter 109. The rst of these occurs when we have been showing black digits and an algebraic subtraction is made so that it is necessary to show red digits-after having passed through zero in order to give the correct algebraic difference. The second instance is where we have been computing below zero and showing red digits and a larger number has been added to a smaller negative uiimber exhibited, making an algebraic addition. Then it is necessary in going up through zero to shift from showing red digits to showing black digits. In the present arrangement the shutter is made to govern its own shifting, first by controlling the shifting mechanism for the shutter, and second by controlling the direction of shift by its own position, That is to say, theshutter itself controls when and how it shall be shifted. Uop'eration is needed, however, ofV other elements which by their position or condition determine with the shutter when it shall be shifted.

The-other elements which cooperate with the shutter are the computing wheel of highest denomination and the subtractionsetting or state-controlling mechanism. The reason for this is that when the shutter is in a position indicating black or positive numbers and the machine is subtracting` with the subtraction-setting mechanism having been operated, and the computing wheel of highest denomination fails to arrive at a 0 position, then an algebraic subtraction has taken place, and it is necessary to shift the shutter to a position exhibiting the red digits in order to disclose the true result. In order to take care of these three conditions -there are provided three interponents (Figs. 9, 11, 19 and 20) indicated at 116,

117 and 118 in the form yof resiliently.

mounted sections of a thrust bar. The interponent 116 may be termed the shutter interponent in that it is controlled from the shutter or shield; the interponent 117 may be called the computing Wheel interponent in that it is controlled from the special or idle computing wheel of highest denomination; and the interponent 118 may be called the state-controlling interponent in that it is controlled from the state-controlling or subtraction-setting mechanism. The shutter interponent 116 may occupy one of two positions indicated b v the letters B and R in Fig. 20 corresponding to the positions of the shutter 109 exhibiting black and red .di 'ta` respectively.

n order that the movements of the shutter 109 may be transmitted to the intel'- ponent 116, a link 119 is connected to the shutter at one end, and at the other end to an arm 120 on, which the shutter interponent 116 is mounted. The arm 120 is pivotall mounted at its lower end so as to swing bac r and forth with the back and forth movements of the shutter 109.

The computing wheel interponent 117 has three positions indicated by 1-8, 9, and 0 in Fi 20. The first of these positions (Fig. 21 the intei'ponent 117 occupies when the computing wheel 87 of highest denomination is rotating with any peripheral point ol the wheel in register with the line of sight other than the 9 and 0 points. The niiddlc position (Fig. 22) of the interponent 117 corresponds to the stopping of the idle computing wheel 87 with the 9 point thereof in register with the line of sight. The third position (Fig. 23) corresponds to the computing wheel 87 with the 0 point thereof in register with the line of sight. To control the several positions of the computing Wheel interponent 117, it is mounted on an arm 121 of a bell crank 122. This bell crank is mounted for a swinging movement and is held at tinies by a spring 123 in the 1-8 position of Fig. 20 (see Fig. 21). When, however, the idle coinputing wheel 87 has been rotated nine-tenths of a revolution, a segmental gear 124 will come into engagement with a corresponding gear 125 on one of the arms 126 of the bell crank 122 so as to swin the computing wheel interponent from tie Fig. 21 position to the Fig. 22 position. If tens should be carried to the computing Wheel 87 of highest denomination so that this Wheel will have rotated for ten-tenths of a revolution, then the 0 point will come to the line of sight, whereby the mutilated gear 124 will pass on one step farther, bringing the intcrponent 117 to the Fig. 23 position and holding it there against the tension of the spring 128. It will be evident that inasmuch as the highest computing wheel 87 in normal adding operation above zero is at a position corresponding to the 0 position at the line of sight, this Fig. 23 position will he the normal position.

The state-controlling interponent 118 has two positions; that shown in Figs. 11 and 19 corresponding to the mechanism carrying on an adding operation, and that shown in Fig. 9 and in full lines in Fig. 20 corresponding to the machine carrying on a subtracting operation. To obtain these two positions the state-controlling inteiponent 118 is mounted on a lever 127 which is pivotally mounted for back and forth swinging movements and is pivotally engaged at 12S by a lever 129 pivotally mounted at v130. The lever 129norinal1y occupies, when the machine is adding, the position indicated in Figs. 11 and 26, but when the subtrac- ,this is that the subtraction tion key 59 is operated to set the machine for subtraction, its rod 61 swings the lever 129 from the Figs. 11 and 26 position to the Fig. 9 position. This shifts the interponent 118 to a position corresponding to the subtracting state. The lever 129 and thus the interponent 118 are locked in this position by a latch 131 (Fig. 9) engaging a pin 132 on the lever 129. The reason for rod 61 returns to its normal position after setting for subtraction and before the subtracting operation takes place.

Allowance is made Fig. 9) for this return movement of the subtraction rod and the key 59 by having a pin-and-slot connection 133 between the lever 129 and the subtraction rod 6l. The latch 131 may be tripped at the end of a subtracting computation so as to permit the interponent 118 to return to an adding position corresponding .to the adding state, which automatically takes effect in the computing mechanism after a subtracting computation, by means of a link 134 which is connected to an Varm 135 on the rock shaft 102, which is operated at approximately the end of the return stroke of the general operator 43 in bringing into play the pin-restoring plate 99.

Whenever the three interponents 116, 117 and 118 are in alinement with each other it denotes that an algebraic (via, crossing zero) summation is taking place, and it is necessary to shift the shutter 109. When the interponents are in alinement in the position shownl in Fig. 9, the shutter will be shifted from showing black above zero to showing red belowzero. When the three interponents are inV their other position of alinement, which would correspond to the lower-three positions in Fig. 20, then the shutter will be shifted from showing red digits below zero to showing black digits above zero. This all takes place automatically, the three interponents when in alinement being used to transmit an impulse which starts slnitter-shifting mechanism into action. For this purpose there is provided on the enel-al operator 43 a one-way acting camming dog 136 (Fig. 9) which is pivoted at 137 so that it can swing idly against the tensionof a spring 138 on the forward movement of the general operator, but on the return stroke of the general operator an extension 139 thereon engages a stop 140 so as to hold this camming dog 136 rigid.

The camming dog 136 will act as a rigid cam on the return stroke of the general operator so that it will cam aside a follower 141 on an arm 142 which is secured to a rock shaft 143. The rock shaft 143 also has secured thereon a widened arm or blade 144 which will engage with the interponent 116 in either position of its adjustment. If the three interponents '116, 117 and 118 are in alinement as in Fig. 9, the rocking ot' the shaft 143 and the swinging of the blade 144 in this manner will 'thrust the interpouent 116 lengthwise against the tension of its spring 145 (Fig. 25), which in turn will move the interponent 117 against the tension of a similar spring 146 provided therefor, so that the interponent 117 will in turn move in the direction of its length the interponent 118 against the tension of a spring 147.

The interponents 116, 117 and 118 therefore form a sectional thrust rod which will transmit the movement of the blade 144 to a similar blade or widened arm 148 secured t0 a rock shaft 149 which swings an arm 150 secured thereto. This arm 150 bears a spring-pressed pawl 151 (Figs. 11 and 15), which is arranged to advance a special mutilated gear 152 which is similar to the tenscarrying mutilated gears `51 and is mounted on the same shaft therewith. There is also provided one of the assisting segments 52 for this special mutilated gear 152. As the pawl 151 moves the mutilated gear around one-ninth of a revolution it displaces the mutilated portion thereof which is normally in register with the associated assisting segment 52 and brings a full or complete tooth in register with the path of movement of such segment. This enables the mutilated gear to be rotated two-ninths of a revolution 100 fartlilen making a third of a. revolution 1n a Secured for rotation with the mutilated gear 152 there is provided a trident or threetoothed gear 153 (Figs. 11 to 14) the teeth 105 of which act as cams engaging a cam head 154 on a lever 155, which is normally held by a spring 156 in a position to be engaged by the teeth of the camming gear 153. Pivotally mounted on the lever 155 there is pro- 110 vided a pawl or dos?` 157 which is normally held in an intermediate position bv a spring 158. Arranged in opposition to the paw] or dog 157 on the shield or shutter 109 there is provided a diverting apex 159 the point of 115 which' lies on the center line between the pivot of the dog 157 and the pivot of the shield 109. At the roots of the apex 159 there are provided shoulders 160 and 161 with which the dog 157 will engage accord- 120 ing to which wav the apex diverts it. That is to say, if the shutter 109 is in the position shown in Fig. 12 showing black. the point of the apex 159 will be slightly below the point of the dog 157 so that as the lever 155 is 125 swung forward. the dog 157 will be diverted upwardly by the cam surface on the upper side of the apex 159. This will bring the dog into engagement with the' shoulder 160, so that a further movement of the arm 155 130 

